body {
  color: #333;
  background-color: #ccc;
  margin: 1em 10%;
}
h1 {
  color: #333;
  background-color: transparent;
}
a{
    color: #c60;
    background-color: transparent;
    font-weight: bold;
    text-decoration: none;
}
ul{
    padding: 0;

}
li{
    float: left;
    padding: 1em;
    list-style: none;
}
.cl::after{
    content: '';
    display: block;
    clear: both;
}
.box{
    height: 500px;
}